Acceleration producing machine



Nov. 17, 1942. P. w. NOSKER ETAL 2,301,957

ACCELERATION PRODUCING MACHINE Filed Sept. 16, 1941 3 Sheets-Sheet 1 Nov. 17, 1942. P. w. NOSKER ET AL 2,301,967

. ACCELERATION PRODUCING MACHINE Filed Sept. 16, 1941 s Sheets-Sheet 3 P404 M4 Nos/(2 K4094. L/ IVE/N rogue/5 Patented Nov. 11, 1942 ACCELERATION PRODUCING MACHINE llaul'w'Nosker, Yellow Springs, and Karl J. Wein, Da Ohio Application September '16, 194 1','seriai No; 411,064

' 10 Claims. (91. vet-151) (Granted under the-act ofMarch 3, 1883, as amended April 30, 1928; 370 0. G. 757) The invention described-herein may be manufactured and used by or for the Government for governmental purposes, Without the payment to us of any royalty thereon.

This invention relates to apparatus for produc-' ing known or determinable accelerations for test purposes.

An object of the invention is to provide a means for producing constant or static accelerations of controllable and computible magnitudes.

Another object is to provide means for producing varying or dynamic accelerations of controllable and computable magnitudes and frequenvcies. V

A further object is to provide mean for producing accelerations having a constant or static component and a superimposed varying or dynamic component, the static component being of controllable and computable magnitude and the dynamic-component being of controllable and computable magnitude and frequency. i

A further object is to provide a machine capable producing determinable'accelerations, for cal-. ibrating accelerometers.

A still further object is to provide a machine capable of producing determinable accelerations, for testing the eifects thereof on various types of instruments, or other devices ofany nature whatsoever within the limitations of the machine.

A still further object is to provide a machine for producing motions of controllable and dfitelr, minable velocities and amplitudes for'calibrating and testing vibration analyzing equipment and the like.

Additional objects and advantages will become apparent to those skilled in the art as the description proceeds in connection with the accompanying drawings in which: I

Fig. 1 illustrates a perspective view of a preferred embodiment of an acceleration producing machine constructed according to the principles of the present invention.

which is to be calibrated or tested. The revolving arm 3 is keyed to a vertical shaft 6 journaled in the base I and pedestal 2, the said shaft be-- ing driven by the horizontal motor shaft 1 through bevel gearing or the like. 8. Shaft l is turned by the motor 9 which has incorporated therewith a tachometer l0. Locking means II are provided for locking the arm 3 against rotation when desired.

The mechanism thus far described will cause movement of the accelerometer in a circular path in a horizontal plane. thereby subjecting it to aconstant acceleration due to centripetal force.

Additional mechanism will now be described for imparting a reciprocating movement to the accelerometer with respect to the arm 3,

Fig. 2 is a fragmentary sectional view showing the manner of mounting the revolving parts, and the manner of making the electrical and air line connections'between the base and the revolving parts.

Fig. 3 is a fragmentary top plan view showing the eccentric mechanismgindetail. 1

In the preferred embodiment of the invention herein illustrated; the moving parts of the machine are mounted upon a. stationary base I, and

a pedestal 2, and comprise essentially a rev'olving arm 3 and a reciprocating mounting table 4 thereby to superimpose a variable component of acceleration upon the constant acceleration due .to revolution. The motive power for the reciprocating movement is derived from a motor 12 having incorporated therein a tachometer l3. A pinion gear I4 on the motor shaft rotates the flywheel l5 which carries an eccentric pin l6 engaged by the yoke I! on the reciprocating rod l8. The reciprocating rod [8 runs through a guide bearing l9 and attaches to the mounting table 4 slidable in guides 20. A counterweight 2| may be provided to balance the arm 3.

Means are provided as best shown in Fig. 3 for adjusting the travel of the reciprocating table 4,

this means comprising a rotatable plate 22 in the flywheel I5 to which plate the eccentric pin I6 is attached. The numeral 23 indicates the location of the center of the vertical shaft 6, which is the center of rotation of the flywheel l5, and the numeral 24 indicates the center of the circular plate 22. The eccentric pin it and the point 23 are arranged to be the same distance from the point 24 so that upon rotation of the plate 22 to the zero position, as indicated by the markings 25, the pin l6 will lie over the center of rotation 23 of the flywheel l5 so as to produce a zero threw in the yoke I1 and reciprocating rod l8. By rotating the plate 22 ina counterclockwise direction, for instance, with respect to the flywheel IS, the eccentric pin it will be moved away from the flywheel center 23 to provide a predetermined throw for the yoke l1, and the length 'of the throw, or a function thereof, may be indicated arcuate path 26 about the center 24, the maximum possible throw being provided when the pin for carrying the accelerometer 5, or other device, It lies on the opposite side of the center 24 from point 23, and a minimum, or zero, throw being provided as stated when the pin i6 is rotated to a position directly over the point 23. If the scale 25 has uniform graduations the plate 22 is preferably provided with a vernierfor accurate positioning. The plate 22 also has associated therewith a suitable clamping means, illustrated generally at 21, for positively securing the circular plate 22 against rotation with respect to the flywheel after a selected adjustment has been made. The clamping means 21 must lie suillciently close to the top face of the flywheel to clear the under side of the yoke II. It is understood that in the operation of the device there is provide some form of locking means such as the machine screw 28 for locking the flywheel i5 against rotation on the arm 3.

With both locking means H and 28 effective,

as illustrated in Fig. 2, no part of the mechanism can operate. Then, if only the locking means H is released, the arm 3 may be caused to revolve at a uniform speed to subject the accelerometer 5 to a constant acceleration. By engaging the locking means Ii and releasing the locking means 28 of the accelerometer 5 may be subjected to a reciprocation in linear simple harmonic motion, thus producing a cyclically varying acceleration. By releasing both locking means II and 23 and energizing both motor means 9 and [2, the mounting table 4 carrying the accelerometer 5 will be subjected to an acceleration having a constant component due to the rotation of the arm 3, and a variable component due to reciprocation of the table 4 upon the arm 3 as it revolves. It will be appreciated that if the angular velocity of the arm 3, the frequency of reciprocation of the table 4, and the dimensional constants of the mechanism are known, the acceleration values may be computed for the various types of operation above described.

The illustrated embodiment further comprises means for accurately controlling the speeds of the motors 9 and I2, and means for indicating the several adjustable quantities necessary for the calculations of acceleration values. For this purpose the arm 3 carries electrical binding posts 29 for connection with the acceleration responsive mechanism of the accelerometer 5. Air line connections 30 are also provided for accelerometers designed to take into consideration air speed along with acceleration. The electrical and air line connections at 29, 39 should be provided with sumcient slack to allow for the intended reciprocation of the table 4. The electrical circuit through 29, the power circuit for the motor I2 and the circuit for the tachometer l3 may be brought together in a cable 29' which enters the shaft 6 for connection of the individual circuits with slip rings 3|. Individual brushes on a brush holder 32 are provided to complete these circuits and carry them by means of the cable 33 to the various electrical connections 34 on the base I. The air lines 30 communicate with passages 35 which in turn open into the annular spaces 36 to maintain air pressure connections with the lines 31 as shaft 6 revolves.

Suitable packing glands are provided around the shaft to prevent leakage into or out of the spaces 33.

The numeral 40 represents an indicating and control panel carrying a pair of tachometer indicators 4| to accurately show the speeds of motors 9 and I2, and a pair 01' speed regulating means 42 including a coarse adjustment and a fine ad- Justment to accurately obtain the desired speed of each motor. Behind the panel 44, appropriate connection is made with a source of power,

not shown. -The air lines 31 lead to a source of differential air pressure, not shown, designed to simulate the action of an air speed indicator under flight conditions. Thegauge 43 indicates the pressure diil'erence existing between the air lines 31 and may be calibrated in appropriate units of pressure or air speed.

The primary advantage of the present acceleration producing machine is that it affords a means for studying the responses of accelerometers and other instruments to static and dynamic accelerations throughout considerable ranges of acceleration amplitude and frequency. The present machine is believed to be the first capable of producing all of the following types of acceleration: constant acceleration, cyclically varying acceleration with no constant component,

and cyclically varying acceleration with a constant component. The present mechanism is designed primarily for calibrating accelerometers but is also equally well suited for testing the effects of accelerations of difierent types upon various other instruments, such as the engine and flying instruments on an airplane, and testing devices which might be applied thereto such as strain gauges and the like. In general, the present mechanism is intended to produce determinable acceleration values in small objects within the capacity of the machine, irrespective of the nature of the objects or the specific purpose to be accomplished. The mechanism is further adapted to produce vibratory motions having controllable and determinable velocities and amplitudes useful in calibrating and testing vibration analyzing equipment and the like.

While we have shown and described but a single embodiment of our invention, it is to be understood that it is capable of many modifications. For instance, provision may be made for accommodating a plurality of accelerometers for simultaneous calibration. This may be done by providing a table 4, capable of holding more than one accelerometer, at the same or diflerent radial distances from the center 23, or a second table 4 may be provided on the other end of the arm 3, in lieu of the counterweight 2|. Also, additional arms 3 may be provided, like the spokes of a wheel, and the motor l2 may be mounted between two of these arms, or directly above the center 23. If a plurality of reciprocating tables 4 are provided, they may be all operated from a common eccentric mechanism, or they may be independently reciprocated by individual eccentrics, or cranks, on the same or different motor means. If it is desired to introduce the acceleration of gravity the revolving arm, or arms, may be caused to rotate in an inclined or vertical plane. All such modifications are within the scope of the invention and these and other changes, therefor, in the construction and arrangement may be made which do not depart from the spirit and scope of the invention as delined in the appended claims.

Having now fully described a preferred embodiment of our invention, and the manner in which the same is 'to be used, what we claim as 1. An accelerometer calibrator comprising means for subjecting an accelerometer to a conmotion, means for locking said table in a fixed position on said arm, and means for locking said arm against rotation.

6. In a machine for subjecting an instrument stantly acting acceleration in a given direction 5 to mechanical motion, a'ba'se, a rotatable arm on with respect to said accelerometer, means for superimposing upon said acceleration a varying acceleration in the same plane, and means operable by said two first namedmeans for indicatin tion experienced by said accelerometer.

2. An acceleration producing machine comprising means for moving an object in a path which is the resultant of two component motions,

said base, means for rotating said arm, a table on said arm adapted to hold said instrument,

indicator connections on said arm for attachvalues determinative of the resultant accelera ment to said instrument, and means for carrying said connections from said rotatable arm to said base to allow for unlimited rotation of said arm.

'7. A testing machine for producing a determinable acceleration which is the resultant of a one ofsaid'components being an-angularmotion constant component and at least one variable in a plane and the other of said components being a reciprocating motion in said plane and in a direction radial to said angular motion, and means operable by said first named means for component which varies sinusoidally with respect a ,to time comprising, a rotatable element, means indicating values determinative of the acceleratatable element and movable radially with retion experienced by said object.

3. An acceleration producing machine comprising means for supporting an object for angular motion in a plane, controllable speed driving means for said first means, means for measspect to the axis of rotation of said rotatable ing means for said rotatable element and means for changing the predetermined frequency and amplitude of the reciprocable motion of said radial to said angular motion and means for 5 support.

measuring the frequency of said simple harmonic motion.

4. A machine for producing mechanical motions comprising an arm mounted on a vertical 9. A testing machine for testing and calibrat-- ing acceleration responsive devices and the like comprising, an arm mounted for rotation in a horizontal plane, adjustable speed driving means axis for rotation in a horizontal plane, a table connected to said arm to cause rotation of the on said arm adapted to hold a device to be subjected to said motions, controllable speed driving means for imparting an angular velocity to said arm about said axis, means for measuring same at a selected speed of rotation, a reciprocable slide mounted on saidarm and sewing as a support for the device to be tested and movable radially with respect to the axis of rotation said angular velocity, controllable speed driving of said arm, an adjustable throw crank mounted means independent of said first mentioned driving means and carried by said arm for imparting a radial reciprocating movement in simple harmonic motion to'said table, means for adon said arm, a linkage connecting said crank to said slide efl'ective to cause a simple harmonic reciprocating motion of said slide, and an adjustable speed driving means connected to said justing the length of stroke of said movement, crank for .driving the same at aselected speed,

and means for measuring the frequency of said harmonic motion. a

5. A machine for producing mechanical motions comprising an arm mounted on a vertical whereby a device to be tested may be subjected to a constant predetermined accelerating force due to the rotation of said arm and subjected simultaneously to a cyclically varying accelerataxis for rotation in a horizontal plane, a table in force due to reciprocation 01 Said Slideon said arm adapted to hold a device to be subjeoted to said motions, controllable'speed driving means for imparting an angular velocity .to said ing the length of stroke ofsaid movement, means 60 for measuring the frequency of said harmonic 10. The structure as claimed in claim 9, in

which there is provided a speed indicating meansoperatively associated with the driving means for-said arm and a separate speed indicating controllable speed driving means operatively associated with the driving means for said crank whereby the angular velocity of the arm and the frequency of the reciprocation of theslide may be determined. 7

PAUL w. NOSKER. KARL J. wnm. 

